Convert USE_BISON to USES= bison
It brings bison as a build dependency in case it is set the following way:
USES= bison or USES= bison:build
it brings bison as a run dependency in case it is set the following way:
USES= bison:run
it brings bison both as a run and build dependency in case it the set the
following way:
USES= bison:both
While here trim some headers
Convert some USE_GNOME= gnomehack to USES= pathfix